The present invention relates to new compositions of matter having antibacterial activity and more specifically to new antibiotics designated XK-62-3 and XK-62-4. The invention also pertains to the production of XK-62-3 and/or XK-62-4 by culturing a microorganism belonging to the genus Micromonospora, which is capable of producing one or both of the active substances in a nutrient medium, until antibacterial activity is detected in the culture liquor and then isolating at least one of the active substances therefrom.
Antibiotics which exhibit activity against a broad spectrum of bacteria are always in demand. To this end, it is known that when certain strains of Micromonospora are cultured in a nutrient medium, several antibiotic substances are liberated in the culture liquor. One such substance is XK-62-2 which is isolated from the culture liquor of Micromonospora sagamiensis MK-65, ATCC 21826 (FERM-P No. 1530), Micromonospora sagmiensis var. nonreducans MK-62, ATCC 21803 (FERM-P No. 1477) and the like. XK-62-2 has the following structural formula: ##STR1##
The chemical, physical and biological properties of XK-62-2 and a process for the production thereof are described in U.S. Pat. No. 4,045,298 issued Aug. 30, 1977.
It has now been found that a new mutant strain of Micromonospora sagamiensis, when cultured, liberates, in addition to XK-62-2, two further active substances. A study of the chemical, physical and biological properties of these active substances indicates that the compositions of matter are new antibiotics which are designated XK-62-3 and XK-62-4.